Synthetic resins such as polymethyl methacrylate resins, polycarbonate resins, polystyrene resins, cyclic polyolefin resins, polyethylene terephthalate resins, and triacetyl cellulose resins have many advantages including light weight, transparency and ease of working. These synthetic resins are currently utilized in a variety of fields including optical disks such as CD and DVD, display windows such as liquid crystal displays and EL panels, and functional films.
On use, resin surfaces are often stained with various contaminants and smudged with fingerprints. Such stains and fingerprint smudges are undesirable. For some optical data media, appropriate surface treatment is carried out for the purposes of improving stain resistance, reducing fingerprint adhesion, and facilitating fingerprint removal. For example, various water- and oil-repellent treatments on the surface of optical data media are contemplated.
One common practice for improving the mar resistance of such surface is by forming a transparent hard coat having mar resistance on the incident surface of optical media where writing and/or reading beam enters. Hard coats are formed by coating a composition on the medium surface and irradiating the coating with actinic energy radiation such as UV for curing the coating, the composition comprising a compound having at least two photoreactive groups such as (meth)acryloyl groups in a molecule, a siloxane compound of cage structure obtained through hydrolytic condensation of an alkoxysilane having photoreactive groups such as (meth)acryloyl groups in the presence of a basic catalyst (see JP-A 2002-363414 and JP-A 2004-143449), or the reaction product of an alkoxysilane having photoreactive groups with colloidal silica or the like. However, since these hard coats are intended solely for improving mar resistance, their crack resistance is poor and the anti-staining effect with respect to fingerprint smudges and contaminants and the ability to wipe off marker ink are not expectable.
Then Japanese Patent Nos. 3,603,133 and 3,572,989 disclose a siloxane compound of cage structure obtained by hydrolytic condensation of an alkoxysilane having a polymerizable functional group and an alkoxysilane having a perfluoroalkyl group in the presence of a basic catalyst. A composition comprising such a siloxane compound is coated and cured into a coating, which is expected to have improved anti-staining property because of an increased contact angle with oleic acid, but is insufficient in marker ink wipe-off and substantially reduced in abrasion resistance.